Really? How many people have 64GB of ram? Most of them still have 8GB some even 4GB.
So far another fail by bitdefender
Even 32GB is quite rare to see, not talking about 64GB RAM then (personally I have Acer Nitro 5, came with 8GB RAM installed, took off 4GB RAM component and replaced with 8GB, so total 12GB now)
700-800MB RAM usage is about what comes straight after installation, without reboot etc. But if 700MB after few days use, then I must say somewhere else is problem than inside AV, of course if screenshots shown with exact bitdefender components using that 700MB RAM, then I could believe it little better.
As going Free version, IMO Kaspersky failed totally with KFA 2019 version. Simply their possible new policy drives new users to buy product to get access for awesome options that were available in 2018 version, but grayed out in 2019 free version, and I do know what I am talking about, as I used KFA 2018 and updated to KFA 2019, and later reinstalled to try again KFA 2019.
BD Free Edition user since then, yeah just because of those grayed out options on KFA 2019 version, my policy.